Prior art in this field includes Japanese Unexamined Utility Model Publication No. Sho 63-10765. A small motor disclosed in this publication comprises a chip type varistor electrically connected to a commutator, a commutator holder for holding the commutator, and a securing ring for securing the commutator to the commutator holder. A concave portion for fitting the chip type varistor therein is provided at a base portion of the commutator holder. As the chip type varistor is inserted into the concave portion, the thickness of the motor is made smaller, thus contributing to the thinning of the motor.
Also, a small motor disclosed in Japanese Unexamined Patent Application Publication No. 2006-115564 comprises a core supported on a shaft, a commutator electrically connected to a coil wound around the core, a brush slidably contacting with the commutator, and an annular varistor supported on the shaft. As the varistor is provided on the opposite side of the brush with the core interposed therebetween, the thickness of the motor case is made smaller, thus contributing to the thinning of the motor.